1. Field of the Invention
This invention relates to elastic supports for supporting stuffing or upholstery of seat or furniture pieces such as beds, divans, armchairs, chairs, car seats and the like, and more particularly to an improved elastic support element or belt of the type referred to and to a textile machine for weaving such elastic support or belt.
The use of elastic belts for supporting the stuffing or upholstery in furniture pieces such as seats, backs, arm rests, backboards, motorvehicle seats and backs, and the like is well known. The elastic belts of this kind at present in use are affected by various disadvantages such as for example a lack of uniform spring suspension because each belt applied to the supporting frame has not the same tension as the other belts which are stretched and applied one at a time, and therefore the more stretched belt "works" more than the other belts and supports alone all the weight of the user, thereby fringing and breaking prematurely and causing also the other belts to fringe and break. These elastic belts have been improved by providing on the elastic threads a spirally wound covering formed of natural or synthetic yarns.
From the Italian Patent No. 955 134 a support of this kind is also known, which comprises an elastic net formed of a net or honeycomb fabric made of rubber threads or the like arranged in the longitudinal or warp direction, which rubber threads are covered with a plurality of spirally wound yarns and preferably crossed in the other or weft direction by non-elastic threads of nylon or cotton or other suitable textile fiber.
However, also this support is affected by drawbacks due to the fact that the plurality of spirally wound yarns, while partially overcoming the drawback of the not-uniform spring suspension, require expensive working operations and the use of a great amount of textile yarn, which makes the spiral winding very expensive.
In an attempt to overcome this drawback, use was made of a yarn spirally wound in one direction and a yarn spirally wound in the opposite direction, but this has not solved the problems that the spiral winding involves.
Therefore the elastic threads covered by a plurality of spirally wound yarns, in spite of the precautions taken, lead to tension differences of the covered elastic threads at the time of their manufacture, what gives effect of false twistings and undulations of the elastic support element obtained thereby.
U.S. Pat. No. 4,728,565 improves the above mentioned support element by covering the rubber warp threads by loops formed chain-stitches, mainly improving the resistance and stability of the net.
However, even this last improvement did not reveal itself a perfect solution, because its continuous use brought to a relative shifting between the warp elastic threads and the weft yarn in given points, with a permanent and increasing alteration of the size ratios of at least some of the components of the net formed by said warp threads and weft yarn. This involves an improper reaction of the support belt or element and a reduced life thereof. To try to overcome this drawback, the support elements or belts were impregnated with a latex, but this gives a bad appearance to the product, reduces its resilient features, hinders the passage of air therethrough and rapidly ages the materials contacting the same, in particular the seat foam.
2. OBJECTS OF THE INVENTION
Accordingly, an object of the present invention is to provide a new elastic support element or belt particularly for the uses as above specified, having new connections between its net components, so to allow an elastic elongation of the element or belt even in specific zones thereof, without permanently modifying the net size ratios and in any case always ensuring a return to the original net configuration.
Another object of the invention is to provide a new elastic support element or belt as above stated having a long use life without the need of being impregnated with latex and without any problem of ageing the materials in contact with the same.
Further objects of this invention are to provide a new elastic support element or belt, of the type referred to, having a particularly good "anatomic behavouir" and good characteristics of vibration and noise dampening, as well as so manufactured in such a way that it can be cut, sewn and so on, without risk to impair its properties or unravel its net as used herein, the term "anatomic behavior" means that the present elastic support element has a sufficient degree of flexibility to conform to the contours of the human body when a person sits on a seat including such support element.
Another object of the invention is to provide a textile machine so improved to be able to weave a support elastic element or belt of the type as above disclosed, and in which the width of the belt can be choosen at will, with the possibility of simultaneously weaving two or more belts, if the machine width allows it.